GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 Engine 🢒 Engine Cooling 🢒 Diagnostic System Check

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the Class 2 serial data circuit or due to a total malfunction of the Class 2 serial data circuit. The specified procedure will determine the particular condition.

    2.

  2. Retrieve PCM DTCs.

    3.

  3. The presence of DTCs which begin with U indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the powertrain control module (PCM).
  3. Attempt to establish communication with the instrument cluster.

Does the scan tool communicate with both the PCM and instrument cluster?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the PCM display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Diagnostic Trouble Code (DTC) List/Type in Engine Controls - 4.6L

Go to Step 4

4

Select the IPC display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Diagnostic Trouble Code (DTC) List - Instrument Cluster/Driver Information System in Instrument Panel, Gauges and Console

Go to Step 5

5

Does the scan tool display any DTCs which begin with a U?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Symptoms